The present invention relates generally to sensor assemblies for use in measuring various parameters of fluids located within containers and, more particularly, to wet-tap sensor assemblies having a movable sensor cartridge for inserting and retracting a sensor relative to the container.
In many industrial applications, sensors are used to provide a wide variety of useful information regarding fluids located within a container. When containers, such as pressurized pipes containing gases or liquids, are at or near full capacity, it is beneficial to have the ability to insert and retract a sensor without allowing the fluid to escape, i.e., wet-tap. The use of a wet-tap sensor assembly mounted externally to a container is recognized as an effective way to measure parameters of the contained fluid without allowing the fluid to escape. For example, with reference to pipes of flowing liquids, such sensor assemblies typically include a housing that mounts over a hole in the pipe and a sensor cartridge that is movably attached to the housing and that defines a bore for receiving a sensor probe. The cartridge movably inserts and retracts the sensor probe relative to the flowing liquid without any interruption to the flow of liquid in the pipe. Such sensor assemblies further include sealing means, e.g., gaskets, for forming a seal between the housing and the cartridge whether the cartridge is inserted or retracted.
When a need arises for the sensor probe to be serviced, repaired, or replaced, the movable cartridge and sensor probe are retracted, forming a seal between the cartridge and the housing and, thereafter, the sensor probe can be removed relatively safely. However, if the cartridge is inadvertently displaced from its retracted position to its inserted position without the sensor probe in place, or if the sensor probe is removed prior to retracting the cartridge, the fluid can escape through the bore of the cartridge. Such fluids can be extremely toxic and grave harm may result if it comes into contact with maintenance personnel. To avoid this risk, the flow of the fluid in the pipe often is reduced or stopped while the sensor is removed, which increases associated costs.
It should, therefore, be appreciated that there is a need for a wet-tap sensor assembly for use in measuring parameters of a fluid located in a container that reduces the risk of escape of the fluid, thereby providing increased safety and related benefits. The present invention fulfills this need as well as others.
The present invention provides a wet-tap sensor assembly for use with containers, such as, pressurized pipes of gases or liquids. The sensor assembly includes a movable sensor cartridge mounted to a housing. The sensor cartridge is configured to be movable between an inserted position and a retracted position. In use, the housing is securely attached relative to an external wall of the container, and the sensor cartridge movably inserts and retracts a sensor probe relative to the contents of the container. With the sensor probe in place, whether inserted or retracted, the assembly has means to prevent the contents from escaping. The sensor assembly includes a locking mechanism that locks the sensor cartridge in the retracted position allowing for removal of the sensor probe while preventing against inadvertent displacement of the sensor cartridge.
The invention also resides in a method operating a wet-tap sensor assembly. The method includes inserting a sensor probe into a sensor cartridge movably mounted to a housing securely attached relative to an external wall of a container, wherein the sensor cartridge is locked in a retracted position. The method further includes unlocking the sensor cartridge and transferring the sensor cartridge from the retracted position to an inserted position thereby exposing the sensing end beyond a lower opening of the housing.
In a detailed aspect of preferred embodiments of the invention, the sensor assembly further includes a cap positioned over an upper portion of the sensor cartridge, e.g., cartridge head, and the cap is configured to prohibit removal of the sensor probe without first retracting the sensor cartridge. The cap can be used to disengage the locking mechanism by rotating the cap a prescribed amount. Preferably, the cap includes a cam surface in an inner cavity of the cap configured to perform the disengagement function. Preferably, the configurations of the cap, the sensor cartridge, and the housing cooperate to require prescribed orientations of cap when performing various functions, e.g., unlocking the sensor cartridge, securing the cap when in the inserted position, and removing the sensor probe.
In another detailed aspect of preferred embodiments of the invention, the locking mechanism includes an engaging device movably mounted to the housing adjacent to the sensor cartridge, and the sensor cartridge defines an engagement region configured to receive the engaging device when in the retracted position, thereby locking the sensor cartridge in place.
Other features and advantages of the invention should become apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.